In this industrial field, protein-based natural high molecular substances such as casein, gelatin, etc. have hitherto been mainly used. In use of such a material, ammonium or potassium dichromate is added as a photo-curing agent to a liquid obtained by dissolving casein, gelatin or the like in warm water, and the resultant liquid is applied to a glass plate by a spin coating method. Next, irradiation with active rays is conducted through a mask to form a latent image of a dyeable layer on the glass plate, followed by development to develop the dyeable layer. Then, the layer is dyed with a dye. Thus, a natural high molecular substances have been used.
In the case of using casein, gelatin or the like, there are problems that such a natural material is putrescible, the quality thereof is not constant but varies widely depending on the origin thereof, resulting in its extremely poor color reproduction, the material is liable to peel off in hot water, the physical properties of the material are greatly deteriorated by heat, working conditions are restricted, and so on. Further, there are problems in dyeing, that the temperature of a dye bath for dyeing or the like is restricted and, therefore, it is difficult to obtain a deep color.
Moreover, the use of casein, gelatin or the like is accompanied by the use of ammonium or potassium dichromate as the photo curing agent and, therefore, there are problems that it is necessary to solve the pollution problem associated with the working process or disposal of the materials, and chromium contained in the gelatin would not be completely removed but would cause bad effects.
The present inventors have studied synthetic high molecular weight materials in order to solve the above-mentioned problems. First, an attempt was made to dye the surface of a substrate by use of a polymer having a basic group or quaternary ammonium salt group having affinity for anionic dyes. The polymer itself is dyeable because of its affinity for the anionic dyes, but the polymer is soluble in water. Therefore, when the polymer was applied to a glass substrate or the like and dyeing was conducted after drying the applied polymer, the coating peeled off from the surface of the substrate into the dye bath in the dyeing process, and it was impossible to accomplish the purpose of the dyeing or to obtain a dyed substrate. Besides, the present inventors have found out that when a photosensitive resin composition obtained by adding an azide compound to a dyeable polymer as a crosslinking agent is applied to the surface of a substrate such as a glass plate and is irradiated with light, it is possible to form a favorably dyeable resin coating free of peeling. This finding is now being put into practical use. However, with the recent requirements for higher resolution quality, speedup of process, energy saving and the like, there has been a request for a further reduction in the quantity of light used for curing a photosensitive resin composition. In general, when the quantity of light used for curing a photosensitive resin composition is insufficient, the resin film obtained is weak, and a film roughening phenomenon takes place at the time of dyeing of the film, resulting in an opaque dyed film. In such a case, dyeability and resolution are also poor. Furthermore, there arise the problems of poor dimensional stability of images, etc. In order to meet the above-mentioned requirements through increasing the photo-reaction rate of the azide compound in the photosensitive resin composition, the effect of addition of various known sensitizers on the increase of the photo-reaction rate was studied, but none of the sensitizers gave a satisfactory effect.